Updated: 27 Aug 2010

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Introduction

A worm farm or bokashi bin can take some of the hassle out of composting.

It’s a long trek out to the compost heap to empty vegetable peelings on a wet night. Is there a better way? A worm farm or a bokashi bin is small enough to keep by the back door or even, in the case of the bokashi bin, inside the house.

We checked out 3 worm farms and a bokashi bin.

How they work

Worm farm

You can make your own worm farm or use a stack of tyres, but the ones you buy are much more convenient. They come in at least two layers: a working layer with a perforated base which holds the scraps and the worms; and a lower layer to collect the liquid that drains from the scraps.

If you have an additional working layer you can place this on top when the original working layer is full and the worms will migrate upwards as you fill it with scraps. If you don’t have this additional layer you’ll have to remove the worms from the working layer before using the compost.

The worms can’t cope with garden refuse such as woody twigs or large quantities of grass clippings and they’re not keen on citrus fruit, onions, leeks or anything spicy or vinegary. You should also avoid using meat, fish, oil, fat and dairy products as these become smelly and can attract flies. The worms slow down in winter so you should feed them less often.

You can use the liquid runoff on your garden but you need to water it down to the colour of weak tea first.

Bokashi bin

The system consists of two buckets that fit one on top of the other and a pack of “Compost-Zing”, a bran-based mixture which contains micro-organisms to ferment food waste.

You put kitchen scraps in the top bucket – including raw and cooked meat – and then sprinkle it with the Zing. When the bucket is full, you set it aside for two weeks (longer in cold weather). You then dig a trench in the garden and empty the bokashi mix into it (an alternative is to put the mix into your compost bin). The mix won’t have decomposed – it’s actually a slimy mass covered with white mould – but the instructions claim that once it’s in the soil it’ll break down quickly.

The top bucket has a perforated base so liquid can drain from the scraps and collect in the bottom bucket. You can put the liquid on the garden but it’s vital to dilute it well – it’s a potent mix and may damage plants if it’s not watered down.